SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '328abca796f307552ec93bac9506c3d07dad363d6aeb5ade7b6ac0f2be7e4a82' 
  AND token = 'q9RWy1FJ8VwMzeigMnbEoltCa3eMJiBW4wY6jiq90Jc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}